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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

We have developed a whole-cortical electrocorticographic array for the common marmoset that continuously covers almost the entire lateral surface of cortex, from the occipital pole to the temporal and frontal poles. This protocol describes a chronic implantation procedure of the array in the epidural space of the marmoset brain.

Abstract

Electrocorticography (ECoG) allows the monitoring of electrical field potentials from the cerebral cortex with high spatiotemporal resolution. Recent development of thin, flexible ECoG electrodes has enabled conduction of stable recordings of large-scale cortical activity. We have developed a whole-cortical ECoG array for the common marmoset. The array continuously covers almost the entire lateral surface of cortical hemisphere, from the occipital pole to the temporal and frontal poles, and it captures whole-cortical neural activity in one shot. This protocol describes a chronic implantation procedure of the array in the epidural space of the marmoset brain. Marmosets have two advantages regarding ECoG recordings, one being the homologous organization of anatomical structures in humans and macaques, including frontal, parietal, and temporal complexes. The other advantage is that the marmoset brain is lissencephalic and contains a large number of complexes, which are more difficult to access in macaques with ECoG, that are exposed to the brain surface.These features allow direct access to most cortical areas beneath the surface of the brain. This system provides an opportunity to investigate global cortical information processing with high resolutions at a sub-millisecond order in time and millimeter order in space.

Introduction

Cognition requires the coordination of neural ensembles across widespread brain networks, particularly the neocortex that is well-developed in humans and believed to be involved in higher cognitive behaviors. However, how the neocortex achieves this cognitive behavior is an unsolved issue in the neuroscience field. Recent development of thin, flexible electrocorticographic (ECoG) electrodes enables conduction of stable recordings from large-scale cortical activity1. Fujii and colleagues have developed a whole-cortical ECoG array for macaque monkeys2,3. The array continuously covers almo....

Protocol

This protocol has been performed on 6 common marmosets (4 males, 2 females; body weight = 320-470 g; age = 14-53 months). All procedures were carried out in accordance with the recommendations of the National Institutes of Health Guidelines for the Care and Use of Laboratory Animals. The protocol was approved by the RIKEN Ethical Committee (No. H28-2-221(3)). All surgical procedures were performed under anesthesia, and all efforts were made to minimize the number of animals used as well as their discomfort.

Representative Results

The whole-cortical ECoG array can simultaneously capture neuronal activity from the entirety of a hemisphere. Figure 4 shows examples of auditory evoked potentials (AEPs) from multiple auditory areas in an awake marmoset. ECoG recordings were conducted in passive listening conditions. Each marmoset was exposed to auditory stimuli, which consisted of randomized pure tones with 20 types of frequency. Then, we calculated AEPs by averaging ECoGs aligned with onse.......

Discussion

For successful implantation, animals should be provided with adequate nutrition before and after surgery. Short operating time is also important to optimize the animal's recovery. Preparations should be finished at least one day before surgery. To reduce operating time, previous craniotomy training with electrode array insertion in terminated animals for other experimental purposes is recommended. Table 1 shows an example of the time course for this protocol.

We modif.......

Acknowledgements

We thank Yuri Shinomoto for providing animal care, training, and awake recordings. The ECoG arrays were manufactured by Cir-Tech (www.cir-tech.co.jp). Furthermore, we would like to thank Editage (www.editage.jp) for English language editing. This work was supported by the Brain Mapping by Integrated Neurotechnologies for Disease Studies (Brain/MINDS), the Japan Agency for Medical Research and development (AMED) (JP18dm0207001), the Brain Science Project of the Center for Novel Science Initiatives (CNSI), the National Institutes of Natural Sciences (NINS) (BS291004, M.K.), and by the Japan Society for the Promotion of Science (JSPS) KAKENHI (JP17H06034, M.K.).

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Materials

NameCompanyCatalog NumberComments
Beaker (100 cc)Outocrave
Cotton ballOutocrave
Absorption trianglesFine Science Tools Inc.18105-03Outocrave
Cotton swab with fine tipClean Cross Co., Ltd.HUBY340 BB-013Outocrave
GauzeOutocrave
Towel forcepsOutocrave
Scalpel handleOutocrave
Needle HolderOutocrave
Iris ScissorOutocrave
Micro-Mosquito ForcepsOutocrave
Adson, 1x2 teethOutocrave
Bone CuretteOutocrave
Micro spaturaFine Science Tools Inc.10091-12Outocrave
Needle Holders, 12.5cm, Curved, Smooth JawsWorld Precision Instruments14132Outocrave
Vessel Dilator, 12cm, 0.1mm tipFine Science Tools Inc.18131-12Outocrave
Vessel Dilator, 12cm, 0.2 mm tipFine Science Tools Inc.18132-12Outocrave
Fine-tipped rongeurFine Science Tools Inc.16221-14Outocrave
Manipurator of a stereotaxic frameGas sterilization
Wrench for the manipuratorGas sterilization
Hand-made fixture for the connectorGas sterilization
Silicon cup for dental acrilGas sterilization
Silicon cup hlderGas sterilization
PaintbrushGas sterilization
PencilGas sterilization
Micro screw, 1.4 mm x 2.0 mmNippon Chemical Screw Co., Ltd.PEEK/MPH-M1.4-L2Gas sterilization
Screw driver for the micro screwGas sterilization
Micromotor handpiece of a drillGas sterilization
Stainless steel burr, 1.4 mmGas sterilization
Stainless steel burr, 1.0 mmGas sterilization
Drill bit, 1.2 mmGas sterilization
Rubber air blowerGas sterilization

References

  1. Fukushima, M., Chao, Z. C., Fujii, N. Studying brain functions with mesoscopic measurements: Advances in electrocorticography for non-human primates. Current Opinion in Neurobiology. 32, 124-131 (2015).
  2. Nagasaka, Y., Shimoda, K., Fujii, N.

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